Device, electrical consumer and method for operating an electrical consumer
By introducing a second switch and an idle device in the ASIC and realizing phase shift control of the switch, the noise problem caused by current regulation in the motor vehicle is solved, frequency doubling and noise reduction are achieved, and cost and noise interference are reduced.
Patent Information
- Application Number
- CN201910748521.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2018-08-15
- Filing Date
- 2019-08-14
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2039-08-14
AI Technical Summary
ASIC control devices used in motor vehicles may cause acoustically perceived vibrations and disturbing sounds when regulating currents. Existing methods require increased frequency to avoid noise, but in some cases the noise is still audible.
By introducing at least one second switch and a second idle device in parallel with the power consumption in the ASIC and using a control unit to realize a 180° phase shift of the switch to double the total frequency and maintain a uniform duty cycle, the active use is combined with or passive idle diodes to reduce power loss or cost.
Effectively reduce or improve the noise emission of the power consumption, and can double the frequency without increasing the switching frequency, reduce costs, ensure a uniform current duty cycle, and reduce noise interference.
Smart Images
Figure CN110837236B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a device for operating an electrical consumer, in particular a solenoid valve, the device comprising at least one circuit and a control unit, wherein the at least one circuit comprises a controllable first switch and a first free-wheeling device which is connected in parallel with the electrical consumer or which can be switched, the control unit being designed to control the first switch by pulse width modulation in order to pass a predeterminable current through the electrical consumer.
[0002] The invention also relates to an electrical consumer, in particular a magnetic hydraulic valve of a motor vehicle, having such a device, and to a method for operating such a device or such an electrical consumer. Background Art
[0003] In motor vehicles, for example, in control devices used in ABS or ESP systems, user-specific integrated circuits, so-called ASICs, are often used to supply defined currents to electrical loads or consumers, in particular to the solenoid coils of hydraulic valves. The current through the electrical load is usually regulated in the following way: the ASIC applies a DC voltage available for the system to the load or consumer at a predetermined frequency and disconnects it again. Due to the inductive part of the electrical load, the current through the load rises as soon as the voltage is applied, and the current through the load drops as soon as the voltage is disconnected again. In order to ensure a rapid drop in voltage in the disconnected state, a freewheeling device, such as a freewheeling device in the form of a passive freewheeling diode, is connected in parallel with the load. When a suitable switching frequency is reached, a relatively constant DC current with a low AC component flows through the load or consumer. This control method is also called pulse width modulation. Depending on the design of the ASIC, different frequencies and therefore different current values can be achieved. Typically, the ASIC is designed so that it can achieve frequencies in the range of 4000 to 10000 Hz. However, the remaining AC component of the regulated current can cause acoustically perceptible vibrations in the consumer. If the ASIC is operated at a constant frequency, annoying interfering sounds may be generated, which can also be heard by the passengers of the motor vehicle, for example. Therefore, it is known to change the switching frequency in the ASIC in order to avoid interfering sounds. However, in some applications, audible noise may remain. In order to avoid this as well, the ASIC must be operated at a higher frequency. Summary of the invention
[0004] The device according to the invention having the features of claim 1 has the advantage that the noise emission of an electrical consumer can be reduced or improved by simple expansion using an existing ASIC, without having to retrofit the ASIC with switches that enable frequencies exceeding the usual frequencies. Rather, it can be achieved cost-effectively that by using a DC part the ASIC can be operated at a frequency that is twice as high as the frequency that can usually be achieved by the ASIC.
[0005] According to the invention, this is achieved in that at least one second switch and a second or switchable freewheeling device are provided in parallel with the load, and the control unit is designed to control the second switch in a phase-shifted manner relative to the first switch for energizing the load. The phase-shifted control makes it possible to double the total frequency of the device, in particular when the second switch is 180° phase-shifted relative to the first switch. If a plurality of further switches are provided, it is theoretically possible to further multiply the total frequency. The phase shift is selected in this case so that a uniform duty cycle is set overall.
[0006] Preferably, at least one diode, in particular a decoupling diode, is connected in series between the load and the respective switch, thereby ensuring that no short circuit is formed when one of the two switches is freewheeling and the other switch is switched on.
[0007] Furthermore, it is preferably provided that the parallel or switchable freewheeling device is designed as an active freewheeling diode of a MOSFET switch. Thus, the active freewheeling diode is actively switched on by the MOSFET during the freewheeling phase in order to reduce the power loss of the device. In particular, in this embodiment, the aforementioned diode is present.
[0008] Alternatively, the corresponding freewheeling device is preferably designed as a passive freewheeling diode, wherein the power loss of the device increases, however. However, as an advantage, less cost expenditure is obtained. In this embodiment, the above-mentioned (decoupling) diode is preferably abandoned.
[0009] The device according to the invention is characterized by an electrical consumer having the features of claim 5. This results in the advantages already mentioned. In particular, the electrical consumer is designed as a solenoid valve, preferably as a magnetic hydraulic valve of a motor vehicle.
[0010] The method according to the invention for operating a device or a consumer having the features of claim 6 is characterized in that the switches are controlled in a phase-shifted manner relative to one another. This results in the advantages already mentioned. In particular, the switches are controlled in a phase-shifted manner such that the current curve of the consumer has a uniform pulse duty cycle.
[0011] Preferably, the switches are controlled such that at the beginning of the current supply process of the load, the switches are initially controlled simultaneously and are controlled with a phase shift relative to one another as the duration increases. This makes it possible to find an optimal phase shift of the frequency.
[0012] Preferably, in order to achieve the phase shift, the switches are activated at different frequencies, in particular from the outset, so that the phase shift increases with each clock pulse until the switches are activated uniformly or equidistantly in time from one another, so that a uniform pulse duty cycle results at the current output of the device or in the load.
[0013] Particularly preferably, the switches are further operated at the same frequency when a phase shift of 180° is reached. That is, once a phase shift of 180° is reached, the frequencies of the ASICs are coordinated with one another so that they have the same value. This reliably ensures that the device continues to operate with a uniform duty cycle. If the device uses two switches, which provide the total duty cycle or the total current of the electrical consumer, a phase shift of 180° is particularly selected. If more than two switches are present, the switches are phase-shifted with respect to one another in accordance with the number of switches, so that a uniform output signal of the device or a uniform duty cycle of the output current is ensured.
[0014] According to a preferred embodiment of the invention, the free-wheeling device connected in parallel with the load is actively switched. For this purpose, the free-wheeling device has in particular a MOSFET switch with an active free-wheeling diode. This results in the advantages already mentioned. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Further advantages and preferred features and feature combinations emerge in particular from the preceding description and from the claims. The invention will be explained in more detail below with reference to the drawings.
[0016] To this:
[0017] Figure 1 A simplified diagram shows a device for operating an electrical consumer according to one exemplary embodiment.
[0018] Figure 2 Graphically shows the switch status, and
[0019] Figure 3 An apparatus according to another embodiment is shown. DETAILED DESCRIPTION
[0020] Figure 1 A simplified diagram shows a device 1 for operating an electrical consumer 2. In the present case, the electrical consumer is a coil 3 of a solenoid valve (not shown in detail here), which can be energized in order to actuate the solenoid valve. The device 1 has an application-specific circuit 4 (ASIC), which is controlled by a control device 5, which can also be a component of the ASIC or the circuit 4, in order to actuate the solenoid valve or the electrical consumer 2.
[0021] The circuit 4 has a first switch 6 and a second switch 7 which can be operated by a control unit 5 in order to connect the load 2 to a DC voltage source U. The switches 6, 7 are connected in parallel with each other and in series with the load 2. Optionally, a diode 8 or 9 is also connected in series between the respective switch 6 and the load or the load 2, for example as a decoupling diode. These diodes ensure that no short circuit is formed when one of the switches 6 is closed and the other switch is open.
[0022] In addition, the circuit 4 has a first idle device 10 and a second idle device 11, which are respectively connected in parallel with the electrical consumer 2 or the load of the electrical consumer 2. Here, the idle device 10 is connected between the first switch 6 and the diode 8, and the idle device 11 is connected between the second switch 7 and the second diode 9. According to the current embodiment, the idle devices 10, 11 are configured as passive idle diodes.
[0023] Therefore, the circuit 4 has two channels through which the electrical consumer 3 can be energized. The switches 6, 7 can be operated independently of each other by the control unit 5.
[0024] Currently, the control unit 5 is configured to control the switches 6, 7 with a phase shift relative to each other, so that the electrical consumer 2 is evenly energized at a high frequency. For this purpose, the switches 6, 7 operate at the same frequency, for example 10 kHz, but with the same frequency having a 180° phase shift, as should be elaborated in more detail. In particular, the switches 6, 7 are controlled here with a pulse width ratio reduced by 50%. Figure 2 In a graph plotted against time t, the switching states S6 and S7 (1 = on, 0 = off) of the switches 6, 7, the frequencies f1 and f2 for operating the switches 6, 7, and the output current i of the overall device 1 beneficial to the electrical consumer 2 are shown.
[0025] Figure 2 By means of the common control of the switches 6, 7 by the control unit 5, the pulse frequencies of the switches 6, 7 can be synchronized with each other. The desired phase shift is currently preferably achieved by the following method: at the start of the current buildup in the electrical load, the two switches 6, 7 start synchronously, but operate at different frequencies for a short time, as shown in, so that the phase shift continuously becomes larger. From the moment t1 when the 180° phase shift is reached, the two switches continue to operate at the same frequency f1. The switching moment t1 is preferably calculated according to the following relationship:
[0026] where f1 is the frequency of the switch 6 and f Figure 2 is the starting frequency of the switch 7, where at the beginning: f
[0027]
[0028] < f1. From the moment t1 onwards, the frequency f2 is increased to the frequency f1. 2，start is the starting frequency of the switch 7, where at the beginning: f 2，start < f1. From the moment t1 onwards, the frequency f2 is increased to the frequency f1.
[0029] From this, it follows that from the moment t1 onwards, the electrical consumer 2 is evenly energized and in particular the noise development of the circuit 4 is avoided.
[0030] According to Figure 1 the embodiment, the idle devices 10, 11 are configured as passive diodes 12, 13, while according to another embodiment, it is provided that the idle devices 10, 11 are configured as active idle diodes 14, 15.
[0031] In this regard, Figure 3 An apparatus 1 is shown by way of example, which has MOSFET switches 16, 17 instead of freewheeling diodes 12, 13, which are controlled by a control device 5 and each have one of freewheeling diodes 14, 15. The advantage of active freewheeling diodes 14, 15 is that the power loss of the apparatus 1 is reduced compared to the previous exemplary embodiments, because the voltage drop across the freewheeling diodes 14, 15 is significantly smaller in the case of MOSFETs 16, 17 due to the low on-resistance. In this case, diodes 8, 9 are preferably present.
[0032] The advantageous device 1 makes it possible to double the maximum frequency of the pulse width modulation by providing the second switch 7 and the second freewheeling device 11. This makes it possible to exclude the operating frequency and the vibrations associated therewith from the audible range for humans without great additional effort.
Claims
1. A device (1) for operating an electrical consumer (2), the device comprising at least one first circuit (4) and a control unit (5), wherein the circuit comprises a controllable first switch (6) and a first free-wheeling device (10) which is connected in parallel with the electrical consumer (2) or which can be switched, the control unit being designed to control the first switch (6) by pulse width modulation in order to supply a predeterminable current to the electrical consumer (2), characterized in that The circuit (4) has at least one second switch (7) and a second freewheeling device (11) connected in parallel with the load or switchable, and the control unit (5) is designed to control the second switch (7) in a phase-shifted manner relative to the first switch (6) in order to energize the load (2), wherein the switches (6, 7) continue to be operated at the same frequency (f1) when a phase shift of 180° is reached.
2. The device according to claim 1, characterized in that The electrical consumer (2) is a solenoid valve.
3. The device according to claim 1, characterized in that A diode (8, 9) is connected in series between the load (2) and the corresponding switch (6, 7).
4. The device according to any one of the preceding claims, characterized in that The parallel-connected or switchable freewheeling devices (10, 11) each have an active freewheeling diode (14, 15) of a MOSFET (16, 17).
5. The device according to any one of claims 1 to 3, characterized in that The parallel-connected or switchable freewheeling devices (10, 11) are each designed as passive freewheeling diodes (12, 13).
6. An electrical consumer (2), characterized in that: A device (1) according to any one of claims 1 to 5 is provided.
7. The electrical consumer (2) according to claim 6, characterized in that The electrical consumer (2) is a solenoid valve or a hydraulic valve of a motor vehicle.
8. Method for operating a device (1) according to one of claims 1 to 5 or an electrical consumer according to claim 6 or 7, characterized in that The switches (6, 7) are controlled with a phase shift relative to one another, wherein when a phase shift of 180° is reached, the switches (6, 7) continue to be operated at the same frequency (f1).
9. The method according to claim 8, characterized in that At the beginning of a current-on process of the electrical consumer (2), the switches (6, 7) are activated simultaneously and, with increasing duration, are activated in a phase-shifted manner relative to one another.
10. The method according to claim 8 or 9, characterized in that: In order to achieve the phase shift, the switches (6, 7) are controlled at different frequencies (f1, f2).
11. The method according to claim 8 or 9, characterized in that: The parallel-connected free-running devices (10, 11) are actively switched.
12. Method for operating a device (1) for operating an electrical consumer (2), characterized in that The method comprises the following steps: - providing at least one first circuit (4), which has a controllable first switch (6) and a first free-wheeling device (10) connected in parallel with the load (2) or switchable; - providing a control unit (5), which is designed to control the first switch (6) by pulse width modulation in order to supply a predeterminable current to the load (2), wherein the circuit (4) has at least one second switch (7) and a second free-wheeling device (11) connected in parallel with the load or switchable, and wherein the control unit (5) is designed to control the second switch (7) in a phase-shifted manner relative to the first switch (6) in order to supply current to the load (2); and - controlling the first switch (6) and the second switch (7) in a phase-shifted manner relative to each other by the control unit (5); and at the beginning of the supply process of the load (2), the first switch (6) and the second switch (7) are controlled simultaneously and in a phase-shifted manner relative to each other with increasing duration.